1. Field of Invention
The present invention relates to a manufacturing execution system (MES) and a manufacturing system. More particularly, the present invention relates to a MES and a manufacturing system with virtual-metrology capabilities.
2. Description of Related Art
A MES is application software for assisting an enterprise to actively collect and monitor production data generated during fabrication procedures since receiving orders, production in process, process control until product completion, thereby assuring the production quality of a product or workpiece, wherein the workpiece is referred to as a wafer in the semiconductor industry and as a glass substrate in the TFT-LCD industry. In the MES, a statistical process control (SPC) system is a main tool for monitoring and maintaining workpiece quality. The objective of the SPC system is to effectively monitor the performance of a process over time so as to verify if the process is at a “state of statistical control”.
Semiconductor manufacturing has very complicated production flow, long processing time and high production cost. To fabricate a 65 nm workpiece, it needs more than 36 material layers, more than 500 processing steps and longer than 50 days for a production cycle time. The average cost for fabricating a 300 mm wafer with 65 nm technology is more than 3000 US dollars. Hence, semiconductor manufacturing heavily relies on the SPC system for quality monitoring.
Referring to FIG. 1, FIG. 1 is a schematic diagram showing tool-monitoring and process-monitoring scenarios of applying a conventional SPC system on semiconductor manufacturing. In the semiconductor manufacturing, the conventional SPC system can be divided into an online monitoring SPC (process monitoring) 30 and an offline monitoring SPC (tool monitoring) 32. When the online monitoring SPC 30 is in operation, several workpieces 10 (such as 25 wafers) in production are first placed on a process tool 20 for treatment, wherein the workpieces belong to one identical cassette or front opening unified pod (FOUP). After the process tool 20 has finished processing the workpieces 10, the workpieces 10 are put back to the cassette and transferred to a metrology tool 40 for inspecting the quality of the workpieces. Generally speaking, the metrology tool 40 may select a sample workpiece (wafer) 12 from the workpieces 10 with a fixed order in the entire cassette for measurement, such as the first wafer in the cassette. Then, the online monitoring SPC 30 performs online process monitoring based on the measurement result of the sample workpiece 12.
When the offline monitoring SPC 32 is in operation, a test workpiece (wafer) 14 used for testing is first placed in the process tool 20 for treatment. After the process tool 20 has finished processing the test workpiece 14, the test workpiece 14 is transferred to a metrology tool 42 for measurement. Thereafter, the offline monitoring SPC 32 performs offline tool monitoring based on the measurement result of the test workpiece 14.
However, the online monitoring SPC 30 can only inspect the sample workpiece 12 selected from the workpieces 10 as a representation of all of the workpieces, but cannot perform workpiece-to-workpiece (W2W) total inspection on all of the workpieces, and also cannot perform process monitoring until the measurement of the sample workpiece is done, thus failing to perform real-time monitoring. The offline monitoring SPC 32 needs to use quite a few test workpieces 14 for performing tool monitoring, which not only increases production cost but also occupies precious production time of the process tool 20, and in addition, the test workpieces 14 cannot accurately represent the quality of the workpieces 10 in production.
Hence, it is desirable to provide a MES and a manufacturing system for overcoming the aforementioned shortcomings of the conventional systems.